Method and apparatus for frozen dessert dispensing

ABSTRACT

A frozen dessert dispensing apparatus is provided with a metering chamber having a predetermined volume into which a frozen dessert product is issued at a uniform constant rate from a bulk source. The time period required to fill the chamber volume determines a characteristic viscosity value of the dessert product which is advantageously used to time the flow of additional frozen dessert product from the source into and through the chamber to a selected point. The total time required to dispense a desired volume is based upon the viscosity measurement. A reciprocating piston arrangement provides gating of the frozen dessert product from the bulk source when in a first position and further acts to extrude frozen dessert product from the metering chamber when set in motion under the command of a controller. The piston arrangement includes a compressible plunger portion which deforms as necessary to prevent accidents or other mishaps from occurring in pinch-off regions of the apparatus.

BACKGROUND OF THE INVENTION

This application pertains to the art of dispensing frozen dessertproducts and, more particularly, to methods and apparatus for vendingfrozen dessert products in consumer selectable quantities.

The invention is particularly applicable to vending apparatus forunmanned sale of refreshments to consumers in malls, places of business,public places or the like and will be described with particularreference thereto although it will be appreciated that the invention hasbroader applications such as chemical mixing operations such as blendingpredetermined portions of different paint colors or any other procedureswhich require automatic fluid dispensing in user-settable quantities.

Frozen dessert dispensing apparatus have heretofore required a full timeon-site operator or sales person to manipulate the apparatus in order todispense various quantities of the dessert into a separate carton oredible cone. This human resource burden is largely due to the primitivevalving mechanisms typically employed in soft ice cream and yogurtdispensers. Those valves are in reality a simple gate mechanism operablein a first position to block the flow of the frozen dessert product froma bulk supply and in a second position to permit said flow through aconduit and toward a dispensing head. As illustrated in U.S. Pat. Nos.4,711,376 and 3,698,206, handles are typically connected directly to thegating mechanisms to provide a rather uncomplicated primitive dessertdispensing apparatus.

Devices of the type described above have become popular over the yearsbut present two (2) major problems from a business perspective. First,an amount of human error is involved in determining the actual servingsize. Although the various plastic and waxed containers used inconnection with frozen dessert products of this type generally define aserving size, the actual precise amount of product served may vary.Oftentimes, product waste is involved or customers are over-served inthe aggregate resulting in a business loss. Further, the costsassociated with an on-site employee may be prohibitive. In certainsettings, it is conceivable that insufficient demand exists for the softfrozen dessert products to warrant the expenditure of an operator'ssalary. In areas where sufficient demand exists, such as where a widevariety of products are sold at a common vending area such as a foodcourt for example, the operator's time may be better served tending tothe consumer's other needs rather than portioning frozen dessertproducts manually.

One solution is an automatic vending apparatus. These have been used inthe past wherein a plurality of pre-packaged frozen dessert productssuch as ice cream bars or ice cream sandwiches are sold directly toconsumers. One downside of this approach is that the consumers arepresented only with predetermined quantity choices.

U.S. Pat. No. 2,559,840 describes an ice cream dispensing device whichis capable of issuing various selectable quantities of the frozendessert product from a bulk storage container. However, the apparatusdescribed in that patent is somewhat limited in that only multiples of apredetermined minimum quantity may be served. This is due to the factthat a fixed measuring chamber is repeatedly completely filled thencompletely emptied into a cup or the like to portion out ice cream fromthe bulk supply. Desired portions which are not multiples of thecomplete chamber volume are not serviceable.

Another apparatus for dispensing measured quantities of a frozen dessertproduct is described in U.K. Pat. Appln. 2,230,057. There, a complicatedmechanism including a ram, valve and cylinder cooperate with a duct todivide a bulk supply of frozen dessert product into predeterminedportions. One drawback with this system is its complicated nature andresultant disassembly and cleaning difficulties. In addition, spoilagemay result because a considerable amount of product residue remains inthe ram, cylinder and duct mechanism between uses.

Accordingly, it is clear that a need exists for a frozen dessertdispensing apparatus which is easy to use, simple to clean and maintainand which is capable of dispensing selectable quantities of the dessertproduct from a bulk source. The present invention contemplates new andimproved methods and apparatus for frozen dessert dispensing whichovercomes all of the above-referred problems and others and provides anapparatus and control method for use therewith which is simple,economical and profitable.

BRIEF SUMMARY OF THE INVENTION

In accordance with the present invention there is provided afree-standing self-contained soft frozen dessert dispensing apparatuscapable of dividing bulk dessert into infinitely variable user-definablequantities over a continuous range.

In accordance with a more limited aspect of the invention, the frozendessert dispensing apparatus includes a refrigerated main enclosureadapted to receive bulk frozen dessert product refill cartridges onto adispensing head. The dispensing head is easily manually removable fromthe apparatus for easy cleaning. A piston within the enclosure engagesthe product cartridge on a first open end to apply a slight constantpressure thereto. The second end of the cartridge is adapted to bepositioned on the dispensing head substantially within the refrigeratedenclosure.

According to a still further aspect of the invention, the dispensinghead includes an outlet nozzle, a cavity or product queue having apredetermined volume and a reciprocal plunger mechanism operable in thechamber. In a first position, the plunger permits frozen product to flowfrom the refill product cartridge and into the measuring chamber throughan opening therebetween. The second position of the plungersubstantially blocks the opening preventing further product flow fromthe bulk source.

In accordance with a still further aspect of the invention, plungertravel beyond that which blocks the flow of frozen dessert product fromthe bulk source induces an extrusion of the dessert product from themeasuring chamber through the dispensing opening thus substantiallycompletely evacuating the chamber of product.

In accordance with yet a further aspect of the invention, a method offrozen dessert product dispensing includes timing the interval requiredto fill the measuring chamber, permitting the frozen dessert product toflow from the bulk source and through the measuring chamber for a secondtime period and lastly completely purging the measuring chamber of thedessert product after the second predetermined time period in order todispense a user-settable product quantity.

The principle object of the invention is to dispense user-definablequantities of a frozen dessert product to achieve portion control in anapparatus which is uncomplicated, easy to clean and maintain, andoperates inexpensively.

Another object of the present invention is to provide a method ofoperating a soft frozen dessert dispensing apparatus which facilitateseasy control thereover. The method includes sensing that the measuringchamber is completely full, determining a second time period forcontinued flow of frozen dessert product through the chamber from a bulksource and operating a plunger to substantially completely purge themeasuring chamber. The step of determining the time period required tofill the chamber can be eliminated when the chamber defines the desiredquantity of dessert.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may take physical form in certain parts and arrangementsof parts, preferred embodiments of which will be described in detail inthis specification and illustrated in the accompanying drawings whichform a part hereof and wherein:

FIG. 1 is a perspective view of a frozen dessert dispensing apparatusembodying the present invention;

FIG. 2 is a front elevational view, partially broken away, of thedispensing apparatus illustrated in FIG. 1;

FIG. 3 is a view of the broken away portion of FIG. 2 in partial crosssection;

FIG. 4 is a cross-sectional view of the dispensing apparatus taken alongline 4--4 of FIG. 3;

FIG. 5 is a cross-sectional view of the dispensing apparatus taken alongline 5--5 of FIG. 3;

FIG. 6 is an electrical block diagram illustrating the logic and controlelements of the dispensing apparatus;

FIGS. 7a-7e illustrate a sequence of operating the apparatus of FIGS.1-5 to dispense frozen dessert portions in variable predeterminedquantities; and,

FIG. 8 is a flow chart setting forth a preferred method of dispensingvariable predetermined quantities from the apparatus of FIG. 1.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein the showings are for the purposesof illustrating the preferred embodiments of the invention only and notfor the purposes of limiting same, the figures show a frozen dessertdispensing apparatus 10 including a dispensing station 12, a bulkproduct section 14 and an interface and control section 16.

With reference first to FIG. 1, the frozen dessert dispensing apparatus10 includes a substantially rectangular refrigerated cabinet 18 whichsits atop a reinforced pedestal 20. The refrigerated cabinet 18 includesa front face surface 22 which may be lettered, brightly illustrated orprovided about its periphery with suitable channel members forsupporting replaceable cardboard or plastic product advertisements,operator instructions or the like. In the preferred embodiment, aplurality of thumb screws are used to secure the panels to the cabinet.At least one of the flat panels illustrated in the figure comprising thecabinet 18 are adapted to provide easy access into the cabinet byauthorized personnel for purposes such as to replace depleted frozendessert stock. In the preferred embodiment, the front panel facing theoperator pivots on hinges (not shown) and is optionally equipped with alock to prohibit unauthorized access. An edge of the front panel closesa normally open magnetic safety interlock switch (not shown) when thepanel is pivoted into a closed position sealing the cabinet 18. Allpower is removed from the device when the door is opened.

The pedestal 20 of the dispensing station 12 includes a substantiallysquare bottom portion defining a solid base 24. The apparatus 10 isthereby suitable for placement onto a support table or countertop in astore or the like. A work surface 26 is defined by the general "L" shapeof the pedestal 20 and may include a drip tray (not shown) such as istypical in the dispensing apparatus art.

The various hardware necessary to accomplish the refrigeration of thecabinet 18 including a compressor, condenser and condenser fan are allhoused within the pedestal 20. Since these components are heavy, theirlocation within the pedestal adds to the overall stability of theapparatus 10. To provide ventilation thereof, a plurality of ventopenings 28 are suitably arranged on the face of the pedestal 20 while asecond set of vent openings 30 are arranged on first and second (notshown) sides of the base as well. One or more groups of these ventopenings may be combined to cooperate providing flow through ventilationfor the air-conditioning hardware housed within the base 24. Vents mayalso be added to the rear panel of the pedestal (not shown). Since it isundesirable that heat may migrate upward from the base 24 towards therefrigerated cabinet 18, proper heat management, such as through use offans and vents, is critical.

With continued reference to FIG. 1, the dispensing station 12 includes aproduct discharge 40 disposed on an interface surface 42 between therefrigerated cabinet 18 and the pedestal 20. This surface is set at anangle to the front face surface as illustrated in order to provide easyoperator access to the product discharge 40. The interface surface 42cooperates with the work surface 26 to provide a handy area within whichto position and fill a product container such as a cup, edible cone ordish. During a product dispensing operating mode of the apparatus, thefrozen dessert product exits the refrigerated cabinet 18 through anopening 44 provided in an outlet nozzle 46. A plurality of teeth orserrations 48 are arranged about the periphery of the generally circularopening 44. This is best illustrated in FIGS. 3 and 4. A suitableescutcheon 50 is provided primarily for aesthetics although someinsulation and support for the outlet nozzle 46 is thereby provided. Theescutcheon 50 also provides support for an infrared transmitter andreceiver pair for sensing the dessert product flowing out from theopening 44. In the preferred embodiment, the infrared sensor pair arecompletely encased by the escutcheon 50 in order to protect the sensorpair from contamination due to contact with the dessert product. Theescutcheon 50 is made of a plastic material having suitable infraredtransmissive properties to enable the sensor pair to cooperativelysense, through the plastic, dessert product flowing between the pair.

A pair of illuminated push buttons 58 are disposed on the pedestal andelectrically connected to controller apparatus housed within theinterface and control section 16. The left push button as viewed in theFigure selects a "regular" size or portion of dessert product while theright push button is used to select a "large" portion.

In addition to the front face surface 22 and the product discharge area40, the frozen dessert dispensing apparatus 10 includes an operatorcommand region 52 including a control panel 54 and a keyed accessclosure 56. In the preferred embodiment, the control panel 54 is hingedto the interface and control section 16 using suitable hinges andtechniques well known in the art. A pair of push buttons 53 are disposedon the control panel and electrically connected to the control apparatushoused within the interface and control section 16 as will be discussedin greater detail below. The push buttons 53 offer cycle initiationoptions to an operator for changing spent product refill containers withfull containers. The left push button of the pair 53 initiates a MANUALRETRACT operation which retracts a piston used to pressurize the refillcartridge. The right push button of the pair 53 initiates a TUBE READYoperation. This operation first drives the piston into the full refillcartridge, then pressurizes the cartridge to a slight standby operatingpressure. The pressure is increased when the dessert is being dispensed.

Three indicator lights and a numeric display 55 are also disposed on thegreater command region 52 of the interface and control section 16. Fromthe left as viewed in the Figure, the lights 57 indicate a DEFROSTcycle, a SOLD OUT condition and a LOAD TUBE condition respectively. Thenumeric display 55 is a two (2) digit segmented display for presentingthe temperature within the refrigerated cabinet 18 derived from athermocouple signal to an operator. The display 55 also functions toalert the operator in the event of a plurality of failures or errorconditions discussed in greater detail below. The indicator lights 57are illuminated to provide convenient visual indicia of the operatingcycle or mode of the dispensing apparatus.

The refrigerated cabinet 18 includes a cooled region 60 as bestunderstood with reference to FIGS. 2 and 3. The walls 62 of therefrigerated cabinet 18 are suitably provided with adequate insulationto discourage migration of heat into the bulk product section 94.

A horizontal support member 64 provides a rigid mount for a rigiddispensing head member 70 shown in FIGS. 2-5 but best illustrated inFIG. 4. The horizontal support member 64 and manually removabledispensing head 70 form the bottom portion of a frame structure 72adapted to receive frozen dessert product refill cartridges 74 thereon.

The dispensing head 70 includes shoulder portions 71 shaped to mate withor otherwise engage a pair of slidable lock members 76 as best shown inFIG. 5. The lock members are adapted to slide vertically on acorresponding pair of guide members 78 (FIG. 3). Although only two (2)guide members and shoulders are illustrated in the preferredarrangement, obviously three (3) or more of each may be used toaccomplish the same result which will be described below. In theposition illustrated, the lock members hold the dispensing head inplace.

The top of the frame structure 72 includes a horizontal cap member 80adapted to slidingly engage the guide members 78 for vertical movementof the cap movement thereover. The vertical guide members 78 areslightly enlarged at their top portions to define friction grip portions79 which engage and fictionally hold the cap member 80 at the top of thecooled region 60 to facilitate removal of the head member 70. A pair ofsubstantially circular grooves 82, 84 defined in the cap member 80 anddispensing head 70 respectively, cooperate to receive and support asubstantially cylindrical rigid sleeve or pocket member 86 therebetween.

The pocket member 86 is of sufficient diameter to closely receive a bulkdessert refill cartridge 90 therein. The refill cartridge 90 may be awaxed cardboard or plastic cylinder containing a fresh supply of afrozen dessert product 94 therein. In the preferred embodiment, therefill cartridge 90 holds about 1.5 gallons of frozen yogurt. A fluidtight interface between the cartridge 90 and the dispensing head 70 ismaintained by a plastic end cap 88 attached to the pocket member 86. Theend cap 88 has an opening for the flow of product into the head. This isbest illustrated in FIGS. 3 and 4.

With continued but particular reference to FIG. 3, the cap member 80slidably engages not only the guide members 78 but also a reciprocatingplunger assembly 100. More particularly, an opening is defined in thecap member 80, the opening being large enough to permit the free travelof a lead screw 102 of the plunger assembly 100 to rotate and slidetherein. The lead screw 102 is connected to a piston head 104 through abearing block 106. The bearing block 106 permits free rotation of thelead screw 102 without inducing a corresponding rotation at the pistonhead 104. The piston head 104 is formed of a semi-rigid compound such asa hard rubber so as to engage the inner walls 92 of the refill cartridge90. As the piston 104 engages the inner wall 92 and is forced downwardas viewed in FIG. 3, the frozen dessert product 94 within the refill 90is urged from the container through an opening 96 provided in thedispensing head 70. Alternately, the refill cartridge may be formed withan integral piston adapted to slidably engage the walls of the cartridgeas well as moving piston 104. Other combinations well known in the artare also possible.

The upper ends of the guide members 78 are fixed to and held spacedapart by a second horizontal frame member 66 which also provides supportfor a pillow block 108 comprising part of the plunger assembly 100. Thepillow block engages the lead screw at a threaded interface 110 and isheld in a spatially fixed location by the second frame member 66.Accordingly, as the lead screw 102 is rotated by an electric torquemotor (not shown), the lead screw and piston 104 attached thereto isadvanced downwardly as illustrated in FIG. 3. The frozen dessert product94 is thereby compressed within the refill cassette 90 constrained toexpand only as far as permitted by the rigid tubular pocket member 86.The electric torque motor (not shown) driving the lead screw 102 isoperated in the preferred embodiment only when there is a need todispense the product. The frozen dessert product 94 is maintained withinthe frozen dessert dispensing apparatus 10 under normal atmosphericpressure until a constant and predefined pressure for ready dispensingthereof is necessary. In the preferred embodiment discussed below, theproduct is pressurized two (2) seconds after a draw valve is commandedto retract. Further, a look up table is used to tailor the pressure onthe product based on the quantity of product remaining in the cylinder.

The details of the frozen dessert dispensing head 70 will next bediscussed with particular reference to FIGS. 3-5. As indicated above,the tubular pocket member 86 along with a corresponding end cap 88 isreceived into an annular groove 84 of the dispensing head 70 providing afluid tight coupling therebetween. A centralized opening 96 in the headpermits the free flow of frozen dessert product 94 from the refillcartridge 90 when the draw valve 120 is in the fully retracted position.The dispensing head 70 includes a dish contour 98 formed between theopening 96 and the annular groove 84 to encourage the flow of frozendessert product 94 toward the centralized opening 96. A plurality ofreinforcement ribs 66 extend radially from the opening 96 to increasethe rigidity of the dispensing head in the dish portion 98. Aninterstitial void or airspace 68 is created by the separation betweenthe reinforcement ribs 66 and the structure supporting the draw valve120. This void or airspace is advantageously used in the frozen dessertdispensing apparatus 10 to provide additional insulation to the frozendessert product 94 within the refill cartridge 90. The dispensing headmay be formed of a unitary solid construction. Finger grip detents 77are disposed in the head to facilitate easy manual removal thereof forcleaning or the like.

As best illustrated in FIG. 4, the draw valve 120 is slidably receivedwithin an elongate cylinder 122 extending from a first open end 124 to asecond end comprising the outlet nozzle 46. When in a fully retractedposition, as schematically represented in FIG. 7b, the draw valveuncovers the opening 96 permitting the frozen dessert product 94 tofreely flow therethrough and into a metering cavity 130 defined by theportion of the cylinder 122 forward of the plunger end 126 of the drawvalve 120. The metering cavity acts as a type of product queue in amanner to be described in greater detail below. At the other extreme endof travel, that is in the fully extended position, the plunger end 126of the draw valve 120 engages the inner surface of the outlet nozzle 46.This is schematically represented in FIG. 7e. Motion of the draw valve120 in the forward direction or to the left as viewed in FIG. 4 from thefully retracted position extrudes measured amounts of frozen dessertproduct from the metering cavity 130 and through the opening 44 in theoutlet nozzle 46. The serrations 48 surrounding the opening 44 give theextruded frozen product a fanciful design appearance. A plurality ofcircumferential O-rings 132 are seated in grooves and provide afluid-tight seal between the draw valve 120 and the cylinder 122.

Since it is possible that an operator may inadvertently insert a bodypart, such as a finger, into the serrated opening 44 during forwardmotion of the draw valve 120, a compression spring 140 having apredetermined spring constant communicates the forward motivating forcefrom a prime mover 160 to the draw valve 120. The spring constant isselected so as to preclude a pinching off of the body part which maycome to be squeezed between the plunger 126 and outlet nozzle 46.

With continued reference to FIG. 4, the compression spring 14O is heldslightly compressed between a spring pocket 142 formed in the draw valveand a forward face 144 of a draw valve shoulder formed on a draw valveplunger 138. A rearward face 148 of the draw valve shoulder 146 engagesa draw valve cap 150 which threadedly engages internal threads 152formed in the draw valve 120. The draw valve cap 150 has a centralopening therethrough of sufficient diameter to accommodate an elongateconnecting portion 154 of the draw valve plunger 138. Similarly, thedraw valve shoulder 146 has an outer diameter sufficiently sized toloosely fit within the draw valve 120 so as to axially slide thereinagainst the force of the compression spring 140. A spring guide member156 engages the compression spring 140 to maintain the spring centeredwithin the draw valve 120 and in square contact with the forward face144 of the draw valve shoulder 146.

The connecting portion of the draw valve mates with a prime mover at aconnection coupling 200. When the head 70 is manually placed on theframe member 64, a circumferential groove 202 on the connection portion154 engages a fork connector 204. The fork connector moves with theprime mover in a manner discussed below.

Lastly, with respect to the dispensing head 70 of FIG. 4, an infraredtransmitter and receiver sensor 162, 163 is provided on the escutcheon50 near the opening 44 for sensing the presence of frozen dessertproduct flowing through the opening. An indication of the presence ofproduct at the sensor in the position illustrated indicates that themetering cavity 130 is completely full of dessert product. The sensorpair 162, 163 is connected to the prime mover 160 on an electricalsignal wire 164 in order to communicate power and logical signalstherebetween.

FIG. 6 illustrates a first preferred embodiment the prime mover anddispensing head assembly schematically. In general, the prime mover 160comprises an electronic controller 166 which includes a microprocessor,memory, and buffering in order to perform the various logical andmotivational tasks described in greater detail below. Electroniccontrollers are readily available, fully configured to support a widerange of applications, the only customization necessary being thegeneration of appropriate control software to follow the procedures setforth below. In the preferred embodiment, the controller includes auniversal controller manufactured by Taylor and is identified by theirpart number X47575. The interface board is also manufactured by Tayloras part number X47573-12.

The electronic controller 166 is connected to the sensor pair 162, 163via a signal wire 164. In addition, the controller 166 is furtherconnected to the pushbuttons 53 on the control panel 54 and theilluminated push buttons 58 on the pedestal 20 via a control panel wirebundle 168.

A stepper motor 170 is directly connected to a stepper motor drivecircuit 174 within the electronic controller 166. A suitable arrangementof stepper motor drive wires 171 carries the logical power signals fromthe drive circuit to the stepper motor. A gear box 180 amplifies thetorque generated in the stepper motor in order to actuate a pillow block182 which threadedly engages a lead screw 184. The draw valve plunger138 is connected to the pillow block 182 and moves therewith accordingto the rotation of the stepper motor under the direction of thecontroller 166.

A second preferred embodiment of the prime mover includes a D.C. motorconnected to the lead screw 184 through a dog clutch responsive tochanges in the direction of rotation of the lead screw. The componentsof this second preferred embodiment perform the same basic functions asthe components illustrated in FIG. 6 and, therefore, no separate Figurewill be referred to or presented.

The dog clutch is annular in shape and includes threads on the innercircular surface thereof adapted for engagement with the threads of theleadscrew 184. The outer circular surface of the dog clutch defines aradially extending key member which is adapted to slidably engage acorresponding keyway groove disposed in the dispensing lead 70. Thekeyway groove extends longitudinally generally along the axis of themetering cavity 130 and draw valve travel.

Using the above specified components, the draw valve 120 is caused tomove along the axis of the metering cavity until reaching the extremeends of travel in either the advance of retract positions. At thoseextremes, the rotation of the D.C. motor no longer causes motion of thevalve due to the "snap off" action of the clutch. The lead screw turnsfreely within the clutch. Upon reversing rotational direction of themotor, the clutch once again re-engages thus converting rotation of thelead screw into linear motion of the draw valve.

A first preferred method of operating the frozen dessert dispensingapparatus according to the present invention will next be discussed withreference to FIGS. 7a-7e and 8 and based upon the apparatus set forth inFIGS. 1-6 above including the first preferred prime mover device.

Initially, the draw valve 120 is held in the position (step 200)illustrated in FIG. 7a. This is referred to as the GATE position becausethe flow of frozen dessert product F is blocked by virtue of the drawvalve covering the opening 96. With the valve in the GATE position, thecontroller 66 reads the volume command from the pushbuttons 58 on thepedestal 20 (step 202). The inputted command will be referred to asVOL_(cmd).

Although the preferred embodiment includes a pair of pushbuttons 58 toset a command volume, through simple modification, a thumbwheel switchor dial may be used as an input device to command volumes of varioussizes from a range of valves.

Next, a retract command is issued from the electronic controller to thestepper motor 170 to withdraw the valve and pressurize the productrefill cylinder permitting the metering cavity 130 to fill with thefrozen dessert product (step 204). The position illustrated in FIG. 7bis referred to as the RETRACT position. As soon as the valve reaches theRETRACT position, a timer is started to count from zero (step 206). Thecounter is permitted to increment while the electronic sensor pair 162,163 is continuously monitored by the electronic controller 166 in orderto detect as quick as possible the presence of the frozen dessertproduct at the opening 44 (step 208). FIG. 7b illustrates the flow G ofdessert product through the opening and toward the sensor.

Once the sensor detects the presence of dessert product at the opening,the timer value is read (step 210). The time to completely fill themetering cavity 130 is T_(seconds).

Since the metering cavity is of a predetermined volume, the timerequired to fill that volume with frozen dessert product is usedadvantageously to indirectly calculate a relative viscosity index of thedessert. More precisely, the flow rate through the opening 96 is knowngiven the volume VOL_(meter) of the metering cavity 130 and the timeT_(seconds) necessary to fill that volume. In the special case that thevolume of the metering cavity is selected to match the minimum commandvolume, or "small" serving size, no flow rate calculation is necessary.

At this point in the cycle, the valve is maintained in the RETRACTposition while the frozen dessert product is permitted to flow H throughthe metering cavity and opening into a suitably positioned cup orcontainer below the outlet nozzle 46. The timer is immediately reset andpermitted to once again count up. The time that the draw valve is to beheld in the RETRACT position is calculated (step 212) according to:##EQU1##

When the time reaches the calculated remaining time T_(remaining) (step214), the draw valve 120 is commanded to traverse its entire stroke(step 216) by the electronic controller to first pinch off the opening96 blocking flow I from the bulk supply as shown in FIG. 7d to a fullyextended position extruding the product in the metering cavitycompletely as shown in FIG. 7e.

In the event that the opening 44 adversely affects the overall flow ratethrough the chamber, a delay time period must be added to the calculatedremaining valve. The delay time period is empirically derived andprogrammed into the controller 166. The delay is based on the physicalconstruction and size of the opening 44 and the resultant flow ratetherethrough.

The draw valve 120 "knows" when to stop since the stepper motor 170undergoes angular displacement responsive to the number of pulses issuedby the drive circuit 174 within the controller 166. The electroniccontroller is programmed to issue only the amount of pulses necessary tofully stroke the draw valve. Also, the controller is programmed to issuethe pulses in the proper logical sequence in order to obtain left andright actuation of the draw valve through the stepper motor and leadscrew combination. After the draw valve has reached its fully extendedposition, as best shown in FIG. 7e, blocking the flow J of bulk frozendessert product, a RETRACT command is issued from the drive circuit 174to the stepper motor to withdraw the draw valve (step 218) to the GATEposition shown in FIG. 7a.

When the second preferred prime mover system is implemented to performthe above-described method, the D.C. motor is command to rotate forpredetermined time periods causing the draw valve to similarly react orextend. The time periods are selected to be long enough to ensure thatfull travel is realized. As described above, the draw valve iseffectively divorced from the lead screw at the extreme ends of travelthrough the action of the dog clutch.

Operational Description

The extruder control consists of a control, an interface, a displayboard, and a motor power supply. All of these boards are required tocontrol the refrigeration, dispensing, and retracting systems.

Cabinet Temperature

The refrigeration control of the control system maintains cabinettemperature between 5° and 15° F. by monitoring the cabinet thermistor.When the cabinet temperature reaches 15° F., the compressor is turned onuntil the cabinet temperature drops to 5° F. A heater is selectivelyused in combination with the refrigeration compressor to aid intempering the cabinet should the temperature drop below 5° F. Theevaporator fans remain on at all times except when the cabinet door isopen or during a defrost cycle. The cabinet temperature is continuouslydisplayed on a two-digit, seven-segment display 55 in an absence ofsystem errors. A failed thermistor, motor current failure, or sensorfailure constitutes a system error. The condenser fans are hard-wired toline voltage and remain on at all times. An operator accessiblepotentiometer (not shown) on the unit determines what temperature rangethe cabinet will be controlled in. If the potentiometer is turned to thefar left, cabinet temperature is controlled between 20° and 30° F. Ifthe potentiometer is turned completely right, the cabinet temperature iscontrolled between 0° and 10° F.

Defrost Cycle

The unit selectively enters a defrost cycle every 6 hours. The defrostcycles occur at 3:00 a.m., 9:00 a.m., 3:00 p.m., and 9:00 p.m. Once indefrost, the defrost indicator illuminates and the unit enters theheating phase of the cycle. In this phase the compressor and evaporatorfans turn off and the heater turns on. When the defrost thermistorreaches 50° F. or the heater safety timer expires, the heater is turnedoff and the soak out timer starts. When this timer times out thecompressor is turned on again. When the defrost thermistor detects atemperature below 30° F., the evaporator fans are turned on and thedefrost cycle is then complete. The defrost indicator turns off at thispoint. The compressor remains on until the cabinet thermistor registersa temperature of 5° F., provided the cabinet thermistor has not failed.The control once again starts cycling the compressor, based on thecabinet thermistor reading, to control the temperature between 5° and15° F. The display registers the temperature of the cabinet based on thedefrost thermistor readings. During regular refrigeration, the cabinettemperature displayed is that of the cabinet thermistor readings.

Heater Safety Timer

A fifteen (15) minute timer begins whenever the heater is turned on andis reset when the heater is turned off. If this timer times out, theheater is turned off immediately to prevent an unsafe condition. Noerror codes are displayed and the unit enters the "soak out" phase ofthe defrost cycle.

Failed Cabinet Thermistor

The control has the ability to detect a bad thermistor. If the cabinetthermistor appears to be opened or shorted, the control cycles thecompressor at a fixed rate and flashes an error code "88" on the display55. In the event of a failed cabinet thermistor, the operator remainsable to dispense the remainder of the product in the tube. When the tubeis sold out or if the piston is manually retracted the piston retractsas usual. However, once the piston is fully retracted, the actuator islocked out until the thermistor is replaced or repaired and cabinettemperature can be monitored again. This allows the customer to sellproduct while waiting for service, but prevents the operator fromcontinually using a malfunctioning unit. The unit still goes throughdefrost cycles as in normal operation.

Failed Defrost Thermistor

If the defrost thermistor appears to be opened or shorted, the unitcontinues refrigerating as usual and an error code "77" flashes on thedisplay 55. The unit skips defrost cycles until the thermistor isreplaced or repaired. As with a failed cabinet thermistor, the operatorremains able to dispense the remainder of the product in the tube. Whenthe tube is sold out or if the piston is manually retracted, theactuator is locked out until the problem is solved.

Door Switch

When the door of the cabinet is opened all outputs, including the doorlight are shut off or disabled except for the defrost heater. If theunit is going through the heating phase of the defrost cycle and thedoor is opened, the heater remains on. If the cabinet is refrigeratingand the door is opened, the compressor and the evaporator fans shut offuntil the door is closed. As a safety feature, if the dispensing motorand/or the draw valve are running when the door is opened, operation issuspended until the cabinet door is closed. If the door is opened duringa draw cycle, the portion size will not be within a specification. Thedraw should be terminated when the door is opened and closed.

Actuator Control

SERVE, RETRACT and PRELOAD are the three modes of actuator operation aredescribed above. The SERVE mode is used for maintaining and dispensingservable product. The RETRACT mode is used for returning the actuator tothe HOME position to permit product tube replacement and does not allowproduct delivery. The PRELOAD mode is used for automatically placing thepiston in the appropriate location for product dispensing in the SERVEmode.

Dispensing Product

In the serve mode, when the small (or large) draw switch 58 is pressed,the draw valve slide motor is activated open. After a 2 second delay,(called the actuator on delay) the dispensing motor is turned on atdispensing speed to pressurize the product in the refill cartridge. Itwill remain on until the control has determined that enough product hasbeen dispensed (see "PORTION CONTROL" for further information). Then thedraw valve slide motor is activated in the closed direction. If during adraw, the full extension switch is hit and the dispensing motor currentoverloads, the control presumes the product tube is empty and enters theRetract mode. However, if the motor current overloads, and the fullextension switch is not active, the control assumes there is anoverload, flashes the sold out light, and enters the Retract mode.

Portion Control

The portion control sensors 162, 163 are located inside the spout guidecover 50. When the product passes through the sensor path, a signal issent to the control indicating product has been sent. For a 5 oz.portion, when the sensor "sees" product, the draw is terminated. For anyother size portion (large), the universal control runs a calculation,based on the time it takes to sense the product, to determine how muchlonger the draw should continue.

Sensor Failure

For any size draw, if no product is sensed fifteen (15) seconds afterthe draw switch is pressed, the draw should automatically be terminated.An error code "55" will flash at 1/2 second intervals on the display 55.If the sensors 162, 163 detect product two (2) seconds after the drawswitch 58 is pressed (after actuator on delay), the draw is terminatedand the error code "55" is displayed. If there is a sensor failure,serving will still be permitted and there is no actuator lockout whenthe product tube is sold out or the piston retracts. A sensor failurecould occur if the sensor area on the spout is dirty. When a successfuldraw is completed, a draw in which the sensor detects product within theappropriate time frame, the display will once again indicate cabinettemperature.

Retract Mode

If the product tube is presumed empty, the manual retract switch ispressed, or a system error occurs, the control enters the Retract mode.Once this mode is entered, the control reverses the piston direction atfull speed until the piston is fully retracted. At this point thecontrol waits for the door switch to open and close again, and thepreload switch to be pressed to indicate that a tube has been replaced.Once this occurs and there are no system errors present, the Preloadmode is entered.

Preload Mode

This mode is used to extend the dispensing actuator at full speed untilit reaches a preset load. When the preload mode is initiated the loadtube light shuts off. The sold out light remains lit during preload.When the preload current is reached, the actuator motor is shut off. Themotor current is a function of the pressure on the actuator. The controlis now in the serve mode, and the actuator is in position to deliverproduct. This feature permits immediate product dispensing on the firstdraw off a new tube. If for some reason a tube is removed but another isnot put in, the motor continues moving forward at full speed until thefull extension switch is reached. The Retract mode is then entered. Thedraw switch is inactive in the Preload mode of operation.

Motor Current

The control measures the actuator motor current to estimate the pressureon the actuator. When the full extension switch is open in the Servemode, if the current exceeds the specified overload current the controlshould flash the sold out light and switch modes to the Retract mode.The actuator should reverse down until the full retraction switch isclosed. To remove the error, replace the product tube with properlytempered product. Note that there should be no nuisance overloadsbecause the control does not rely on a fuse. If no motor current ismeasured at any time when the actuator should be operating, the actuatoris shut off and an error code "66" is flashed on the seven-segmentdisplay.

Sold Out Light

In the Serve mode, when the full extension switch on the actuator closesand a current overload occurs, the sold out light illuminates. Thislight will remain on until retraction, and preload are completed. Ifthere is a motor current overload, the sold out light should flash. Thelight will flash during retraction and until the preload mode isentered. When the preload mode is entered, the light will stay on solid.In general, any time this light is on or flashing, product can not bedispensed.

Load Tube Light

In the Retract mode, this light illuminates when the full retractionswitch is closed. This indicates that the piston is fully retracted. Theload tube light however should flash if there is a power failure. Thelight should flash unit it is reset. The light should be reset when thecabinet door is opened and closed, and the tube loaded switch isactivated, indicating that the product tube has been changed.

Power Up

When the system powers up, the mode it is in should depend on how longthe system has been without power. If the power has been out for lessthan 30 minutes, the power-up mode should be the same as the mode it wasin when power when out. If the power has been out for longer than 30minutes, the unit should power up in the retract mode (thus retractingthe piston) and the sold out LED should flash at 1/2 sec. intervals onthe display until a new tube is loaded. Once the full retraction switchis activated, the load tube light will also flash at 1/2 sec. intervalsunit a new tube is loaded. This condition can be distinguished between acurrent overload situation because both sold out and load tube lightswill be flashing when fully retracted. In a current overload situation,the sold to light will be flashing but the load tube light will be oncontinuously when piston is fully retracted.

Clock Set

The control is equipped with a real time clock that is factor set andmanually adjustable. The time is only displayed when manually settingthe clock. In order to set the clock, the manual retract switch must bepressed while the piston is in the fully retracted position. Note thatthe actuator will be disabled during this function. Once the clock setfunction begins, the double digit seven segment display will display thehour of time. If it is p.m., the right decimal point will beilluminated. To change the hour, press the small draw switch button andrelease, the hour will increment each time the draw switch is pressed.Once the desired hour is displayed, press the manual retract switch. Thehour is now set and the minutes will be displayed. To adjust theminutes, proceed in the same manner as before. When the desired minutesare displayed press the manual retract switch, the time will be set andthe control should then exit the clock set function. When the clock setfunction is used, if not activity on the switches occurs for 20 seconds,the control should exit the clock set function with no changes made tothe real time clock. This feature will help to prevent accidental misuseof the clock set function.

Programming Jumpers

The extruder interface board allows for programming jumpers to adjustpreload and overload current values. By placing a shorting tab (the sameas used on the slush interface board) on a particular jumper location,the preload and overload current setpoints will be adjusted.

The invention has been described with reference to the preferredembodiment. Obviously, modifications and alterations will occur toothers upon the reading and understanding of this specification. It ismy intention to include all such modifications and alterations insofaras they come within the scope of the appended claims or the equivalencethereof.

Having thus described the invention, I now claim:
 1. A method ofdispensing a material in a preselected volume greater than apredetermined minimum volume from a source of the material to a selectedpoint comprising:providing a chamber having a predetermined volume nogreater than said minimum volume; flowing material at a substantiallyconstant first rate from the source of the material to the said chamberand determining the time period required to fill the chamber; flowingmaterial from the source into and through the chamber to the selectedpoint for a total time that is a multiple of the determined time period,said multiple being substantially equal to one less than the ratio ofthe preselected volume to the chamber volume; and, terminating the flowand discharging the entire volume of the chamber to the selected pointat the end of the said total time.
 2. The method as defined in claim 1wherein the step of discharging the entire volume of the chamber to theselected point is performed subsequent to terminating flow to saidchamber.
 3. The method as defined in claim 1 including the stepsof:providing a valve for controlling flow of the material between thesource of the material and the chamber; and, actuating the valve to anopen position to begin the timed period; and, closing the valve aftersaid total time which is a multiple of the determined time period. 4.The method according to claim 3 wherein the step of discharging theentire volume of the chamber includes actuating the valve in the chamberto displace the material from within the chamber.
 5. The methodaccording to claim 1 wherein the step of flowing the material from thesource to the chamber includes flowing the material through a firstorifice having a size defining said first rate.
 6. The method accordingto claim 1 wherein the step of flowing the material through the chamberincludes flowing the material through a second orifice having a sizedefining a second rate of flow.
 7. The method according to claim 6wherein the step of flowing the material through the second orificeincludes flowing the material through the second orifice at the secondrate of flow which is substantially equivalent to said first rate. 8.The method according to claim 6 wherein the step of flowing materialfrom the source into and through the chamber includes flowing thematerial through the chamber to the selected point for a total time thatis said multiple of the determined time period, the multiple being equalto one less than the ratio of the preselected volume to the chamber plusa delay time based on said second rate of flow.
 9. Apparatus fordispensing a material in a preselected volume no less than apredetermined minimum volume comprising:a source of material, saidsource having an outlet and discharge means for discharging the materialfrom the source through the outlet at a generally constant rate; achamber connected to the outlet, said chamber having a volume at leastas great as said predetermined minimum volume; timing means fordetermining the time period required for material discharging from thesource through the outlet to fill the chamber to the predeterminedminimum volume; and, control means operatively connected with the timingmeans for terminating flow of material through the outlet to the chamberwhen the total time of discharge of material from the source to thechamber is a multiple of the time period required to fill the chamber tothe predetermined minimum volume, the multiple being equal to themultiple which the preselected volume represents to the predeterminedminimum volume.
 10. Apparatus as defined in claim 9 wherein the controlmeans includes adjusting means for varying the preselected volume. 11.Apparatus as defined in claim 9 wherein the control means includes valvemeans for stopping flow of material through the outlet.
 12. A method offluid portioning for use with a fluid dispensing apparatus including asupply of fluid in a fluid supply chamber connected by a valve to afluid queuing chamber having a fluid discharge opening, the methodcomprising the steps of:determining a volume V of a fluid to issue fromthe apparatus; filling the fluid queuing chamber evenly over a firsttime period T by flowing a volume v of said fluid from said fluid supplychamber to said fluid queuing chamber at a first rate; over-filling saidfluid queuing chamber for a second time period T' by flowing additionalvolume (V-v) of said fluid from said fluid supply chamber at said firstrate to said fluid queuing chamber and out through said fluid dischargeopening according to

    (T/v)*(V-v)=T'

; and, after expiry of said second time period, purging said fluidqueuing chamber by flowing a residual volume v through said fluiddischarge opening.
 13. The method of fluid portioning according to claim12 wherein the determining step includes reading an input from a user assaid volume V of a fluid to issue from the apparatus.
 14. The method offluid portioning according to claim 13 wherein the determining stepincludes storing the input read from the user in a memory in theapparatus.
 15. The method of fluid portioning according to claim 12wherein the filling step includes filling said fluid queuing chamberwith said fluid at a constant rate over said first time period T. 16.The method of fluid portioning according to claim 15 wherein theover-filling step includes flowing said additional volume (V-v) of saidfluid from said fluid supply chamber at said first constant rate to saidfluid queuing chamber and out through said fluid discharge opening.